Isabella Tree at Knepp

Isabella Tree, award-winning conservationist and bestselling author, was conferred an Honorary Doctor of Science at the University of Sussex’s Summer Graduation 2024.

A large skein of greylag geese swoops and glides onto the enormous lake behind Knepp Castle. 

“In the past, we would have seen them as bad news,” says Isabella Tree, who lives with her husband, Charlie Burrell, here at his ancestral home. “It would have meant they were eating our crops.”

Now the geese are welcomed to their 3,500-acre estate in West Sussex, along with an abundance of other native creatures and plants.

For the past 24 years, Isabella and Charlie have gradually turned what was a failing farm into a natural haven for wildlife. 

The results so far are breathtaking. Rare and endangered species, such as nightingales, turtle doves and purple emperor butterflies, have taken up residence. Old English longhorn cattle (an ancient breed once commonly seen in the UK), Exmoor ponies and Tamworth pigs roam freely. Beavers – hunted to extinction in England in the 16^th century – are dam building after being reintroduced in 2022. And white storks now nest in oak trees and a disused chimney at Knepp Castle – the first to breed in the UK for over 600 years.

The Knepp Rewilding Project is not only helping to restore biodiversity in the region, but also providing a rich resource for scientists. 

University of Sussex biologists Dr Chris Sandom, who specialises in rewilding, and Professor Dave Goulson, an expert in bee ecology, are among those who have carried out research on how restoring natural landscapes is affecting flora and fauna.

They have also run modules on conservation in practice at the estate for undergraduates and postgraduates, and supervised student projects ranging from counting dung beetles to recording the sounds of wildlife (ecoacoustics) to assist in measuring biodiversity..

Students say they are excited to be involved in the projects, knowing the data they are collecting is contributing to important studies.

"sleepless nights"

 Isabella's  award-winning account of their departure from industrial agriculture Wilding - The return of Nature to a British Farm, has also inspired a documentary (Wilding) that is now packing out cinemas. But she admits a love of nature was not the initial driver of the project.

Charlie had inherited the land from his grandparents and, although the estate had been farmed for generations, its poor-quality clay soil was too challenging to make the farm profitable.

“We were £1.5m in debt, we had sleepless nights, people’s jobs were on the line, and we were looking at ever more mounting debt while trying to stay competitive,” remembers Isabella.

With the help of stewardship grants, they were able to clear their debts and look into other uses for the farm buildings, which became offices, light industry, and storage units.

But, as sustainability and loss of biodiversity became critical issues nationally and globally, Isabella and Charlie realised that there was something they could do to help.

Through consulting experts and scientists, and visiting rewilding projects in the Netherlands, they learned what would happen if they left their land and its inhabitants to nature – intervening only to keep the system moving and dynamic. 

“We didn’t do it in one fell swoop,” says Isabella. “We began with the area around the house because that felt right. We could hear the insects coming back, something we hadn’t even noticed we were missing as farmers. And we could feel the earth coming back to life.”

As they researched it further, it became apparent that rewilding Knepp would benefit nearby farmers, even if they didn’t change their farming methods.

Isabella says: “We need rewilding as the life support system of farming of food production, because without it we don’t have the pollinating insects, we don’t have the soil restoration to such a degree, and we don’t get dung beetles all year round [a valuable food source for little owls and other birds] because farmers bring animals in during the winter.”

Rewilding also helps to replenish the water table, mitigates flooding, creates physical buffers to protect land from drought and strong winds, and helps to create micro-climates for food production, she says.

Although the initial “mess” of Knepp and the proliferation of weeds (until nature’s own pest controllers restored the ecosystem) generated anger from the local community, the success of the project has led to wide support and even new collaborations.

"nature rebounds if you let it"

 The Weald to Waves project, inspired by Knepp, involves local farmers, landowners and communities willing to be involved in creating ribbons of wildlife corridors throughout Sussex.

“You cannot have individual pockets of biodiversity because they are doomed to fail,” points out Isabella. “And already biodiversity is crashing in them. We need to have these ribbons to connect them.”

Isabella, who began her career as an environmental journalist for Geographical magazine and has authored five other books, believes the success of Wilding, published in 2018 and winner of several awards, is all down to timing.

“If I had written it earlier, I don’t think it would have done anything. But then we had Extinction Rebellion, we had Greta Thunberg, Sir David Attenborough was saying we had a problem, and we had a plastics revolution… Everything was kicking off and there was a general feeling that we cannot trust governments to put nature first.”

She adds that there was also the beginning of a bigger expression of eco anxiety. “There’s a planetary crisis here, but also a feeling of impotence. How can a single person make a difference?

“We are not going back to where we were before. We have altered the planet already. But what we can do is use the tools we have at our disposal to allow nature to evolve itself, to answer these problems.”

The project has shown that nature rebounds if you let it, she says. She has plenty of evidence to back her claim: around 60 singing nightingales last year, increasing numbers of turtle doves (“sadly probably too late to save them from extinction in Britain”), and ongoing independent surveys and monitoring.

“One thing we are beginning to appreciate is that it’s not just the headline species, it’s the abundance. The earthworm or the crane fly may not be exciting species but they are food for everyone else. The more life there is, the more life there is.”

"we didn't envisage the project would be so successful"

The project, which also involves their daughter Nancy doing fieldwork on the estate for her PhD at Oxford into the carbon storage of rewilding at Knepp, and son Ned running the Wilding Kitchen café and restaurant, is now commercially viable.  They produce 75 tonnes of organic meat from the herds of cattle and deer every year, have created an organic market garden next to the restaurant and shop, and they run safaris and glamping and camping in the heart of their wilderness.

“We didn’t envisage this project would be so successful; that within ten years we would have a thriving eco-tourism business,” says Isabella.  “We thought if we could increase biodiversity just a little, that would be a really interesting experiment.

“Charlie and I were sitting outside the other day and wondering What would we be like if we had never done this? He would still be a farmer probably looking into regenerative agriculture by now. But we would be totally different people. It’s an extraordinary thing, what rewilding – putting nature in the driving seat – does to you psychologically, it gives you a sense of your place on the planet.” 

In 2023, Isabella and Charlie received the Zoological Society of London’s Silver Medal for outstanding contributions to the understanding and appreciation of zoology. 

While recognition for their achievements is gratefully received, the real reward is seeing what is happening to their land.

“Nature is so much bigger than us. The systems, the processes, the powerful resilience of evolution – there are things we haven’t even begun to understand. It’s fascinating and humbling.”